Chapter IV: The Glaciers

As introductory to a description of the Arctic Glaciers, a few words on the formation of snow seem necessary. Briefly, it may be said that snow is the result of the crystallization of water.

The molecules and atoms of all substances, when not constrained by some external power, build themselves up into crystals. This is true of the metals and minerals, if, after having been melted, they are allowed to cool gradually. Bismuth develops the process in a very impressive manner, and when properly fused and solidified exhibits large-sized crystals of singular beauty.

In like manner, sugar dissolved in water produces, after evaporation has taken place, crystals of sugar-candy. The ready crystallization of alum is known to every school-boy who has dabbled in “chemical experiments.” Chalk dissolved and crystallized becomes Iceland spar, and assumes a variety of fanciful and graceful shapes. The diamond is crystallized carbon; and the crystallizing power is inherent in all our precious stones,--sapphire, topaz, emerald, beryl, amethyst, ruby.

In the process of crystallization, it is found that the minutest particle of matter is possessed of an attractive and a repellent pole, and that by their natural action the form and structure of the crystal are determined.

The attracting poles, in the solid condition of any given substance, are firmly interlocked; but dissolve the cohesion by the application of sufficient heat, and the poles will recede so far as to be practically beyond each other’s range. And thus the natural tendency of the molecules to build themselves together is neutralized.

Water, for example, as a liquid is, to all appearance, without form; but when sufficiently cooled, its molecules are brought under the influence of the crystallizing force, and then arrange themselves in the most varied and beautiful shapes. When snow falls in calm air, the icy particles present themselves in the form of six-rayed stars. From this type there is no departure, though the appearance of the snow-stars in other respects is infinitely varied.

It is worth pausing, as Professor Tyndall remarks, to think what wonderful work is going on in the atmosphere during the formation and descent of every snow-shower: what “building power” is brought into play! and how imperfect seem the productions of human minds and hands when compared with those produced by the forces of Nature!

We have spoken of attracting and repelling poles; but a few words of explanation seem desirable. Every magnet possesses two such poles; and if iron filings be scattered over a magnet, each particle becomes also endowed with two poles. Now suppose that similar particles, devoid of weight, and floating in the atmosphere, come together, what will happen? Obviously, the repellent poles will retreat from each other, while the attractive will approach, and ultimately interlock. Further: if the particles, instead of a single pair, possess several pairs of poles arranged at definite points over their surfaces, you can then picture them, in obedience to their mutual attractions and repulsions, building themselves together in masses of definite shape and structure.

You have, then, only to imagine the aqueous particles in cold calm air to be gifted with poles of this description, compelling the said particles to assume certain definite aggregates, and you have before your mind’s eye the invisible architecture which creates the visible and beautiful crystals of the snow.

The important part played by this crystallizing force in ice as well as snow, will be understood from the following remarks by Professor Tyndall, who may justly be described as the most eminent living authority on the subject:--

At any temperature below 32° F.,--that is, freezing-point,--the movement of heat is sufficient to loosen the molecules of water from their rigid bonds of cohesion. But at 32° the movement is so diminished that the atoms lock themselves together, and unite in a solid. This act of union, however, is controlled by well-known laws. To the unintelligent eye a block of ice seems neither more interesting nor more beautiful than a sheet of glass; but to the instructed mind the ice is to the glass what an oratorio of Handel is to the scream of a ballad-singer. Ice is music, glass is noise; ice represents order, glass confusion. In the latter, the molecular forces have brought about an inextricable intertangled network; in the former, they have woven a rich and regular embroidery, the designs of which are infinitely beautiful.

Let us suppose ourselves examining a block of ice. In what way shall we get at its structure? A sunbeam, or if that be wanting, a ray of electric light is the anatomist to which we must confide the work of dissection. We direct this ray straight from our lamp across the plate of transparent ice.

It shivers into pieces the icy edifice, exactly reversing the order of its architecture.

The crystallizing force, for example, had silently and systematically built up atom after atom; the electric ray dislocates them (so to speak) just as silently and systematically.

We elevate the ice-block in front of the lamp, so that the light may now pass through its substance. Compare the ray as it enters with the ray as it makes its exit; to the eye there is no perceptible difference, and its intensity seems scarcely diminished. But not so with its heat. As a thermic agent, the ray was more powerful before its entrance than it was after its emergence. A portion of its heat is arrested, is detained in the ice, and of this portion we now proceed to avail ourselves. What will it effect?

We place a lens in front of the ice upon the screen. Now, observe this image (see Illustration), the beauty of which is still very far from the real effect. Here is one star; yonder is another; and in proportion as the action continues, the ice appears to resolve itself more and more into stars, all of six rays, like snow-crystals, and resembling a beautiful flower. By moving the lens in and out, we bring new stars into sight; and while the action continues, the edge of the petals is covered with indentations like those of the leaf of a fern. Probably, few of our readers have any conception of the magical beauties concealed in a block of ice! Let them remember that prodigal Nature works in this way throughout the whole world. Every atom of the solid crust which covers the frozen waters of the North, has been wrought out in obedience to the law we have enunciated. Nature is always and everywhere harmonious; and it is the mission of Science to awaken us to an appreciation of its concords.

There is another point of our experiment to which the reader’s attention must be directed. He sees the flowers illuminated by the ray which traverses them. But if he examines them, while turning upon them a ray which they will reflect and send back to his own eye, he will see in the centre of each a spot with the brightness of burnished silver. He will be tempted to think that this spot is a bubble of air; but, by immersing the ice in hot water, you can melt the ice all around the spot,--and when it alone remains, you will see it diminish and disappear without any trace of air. The spot is a vacuum. Such is the faithfulness to herself with which Nature operates; thus, in all her operations, does she submit to her own laws. We know that ice, in melting, contracts; and here we arrest the contraction, as it were, in the very act. The water of the flowers cannot fill the space occupied by the ice which by its fusion has given birth to them; hence the production of a vacuum, the inseparable companion of each liquid flower.

The fragment of compact ice whose elements assume such beautiful crystalline forms is itself a crystal. This was shown by Sir David Brewster, who employed for the purpose of analysis that modified form of light which we call _polarised light_. It is singularly well adapted to bring out the peculiarities of the main structure of substances, owing to the coloured figures which it outlines on a screen after passing through them. All crystals with an axis--such, for instance, as Iceland spar--yield a series of brilliantly-tinted rings, traversed by a regularly-formed cross entirely black. As ice produces the same figures, we are justified in attributing to it the same kind of crystallization. We must note, however, that we are referring now to the thick ice formed on our canals and lakes. If we examined the first film formed on the surface of the water, we should discover in it a completely irregular crystallization, the ray of polarised light producing only a mosaic of varied tints, distributed without any order. But it is easy to explain the way in which this primary crust or film is produced. Those portions of the fluid mass in contact with the air are the first to freeze, but each molecule of ice abandons its heat to the contiguous water, which thereby is slightly raised in temperature, and the result is a partial congelation. The surface we are examining then presents a network of fine needles intercrossed in every direction, and forming a kind of delicate lace, the meshes or intervals of which are gradually filled up. When the network is transformed into a continuous sheet, the loss of heat is diminished more and more as this external crust grows thicker and thicker; but the development of the ice invariably takes place by means of long interlaced needles, as the reader may see for himself by breaking off a portion from the nearest pond (in winter), and examining the sectional surface.

Having said thus much in reference to the crystallization of ice and snow, we proceed to explain the _regelation_ and _moulding of ice_. Some years ago, Faraday astonished the scientific world by a very curious experiment. Splitting into two parts a piece of ice, he brought together the parts at the moment that fusion took place on their surfaces, and they united immediately. How are we to account for this effect, which can be produced even in hot water?

When the temperature of water rises, the surface molecules first become liquid, then gaseous; being placed beyond the coercitive action of the surrounding particles, they are easily set free; transported, on the contrary, into the centre of the mass, they are brought absolutely under the influence of this action, which induces a new solidification,--or, to use the scientific term, a _regelation_. In this way it becomes easy to understand how very various forms can be communicated by simple pressure to a fragment of ice. If the observer successively places a straight bar in moulds of increasing curvature, he may easily compel it to assume the shape of a ring or even of a knot. In each mould, it is true, the ice breaks; but if the pressure is kept up, the surfaces of the fragments are brought into contact, and adhere so as to re-establish a condition of continuity. A snowball may thus be converted into a sphere of ice, and the sphere, by constant pressure, into a cup or a statue.

Professor Tyndall refers to a remarkable instance of regelation which he observed one day in early spring. A layer of snow, not quite two inches thick, had fallen on the glass roof of a small conservatory, and the internal air, warming the panes, had melted the snow so far as it was in immediate contact with them. The entire layer had slipped down the pane, and projected beyond the edge of the roof, without falling, and had bent and curved as required, just like a flexible body.

The snow-fields which overspread the upper part of every glacier, whether in the Arctic Regions or elsewhere, are composed of crystallized snow, whose fragile, delicate, and fairy-like architecture endures so long as it remains dry, but undergoes a great transformation when the sun, melting the upper stratum, allows the water to interpenetrate its substance. The fluid, congealing anew during the night, transforms the snow into the condition technically known as _névé_; a term given by the Swiss physicists to a granular mass composed of small rounded icicles, disaggregated, but more adhesive than snow-flakes, and of a density intermediate between that of snow and that of ice. Under the pressure of new layers, and as a result of infiltrations of water, the _névé_ unites, and solders into ice of constantly increasing compactness.

But glacier-ice presents some other curious peculiarities. Every abundant snow-fall on the summit of the mountains forms a layer easily distinguishable from preceding layers--which, in most cases, have already passed into the _névé_ condition. This stratification becomes more apparent when the whiteness of the surface has been sullied by dirt or dust wafted on “the wings of the wind.” It is perceptible also in ice; but here we must not confound it with another phenomenon of which the cause is different, the _veined structure_.

In places where glaciers have been accidentally cut down in an almost vertical direction, the section is found to exhibit a series of parallel veins, formed by a beautiful and very transparent azure ice in the midst of the general mass, which is of a whitish colour, and slightly opaque.

In different glaciers, and in different parts of the same glacier, these blue veins will vary in number and intensity of colouring. They are specially beautiful in crevasses of recent formation, and on the sides of channels excavated in the ice by tiny rills resulting from superficial fusion. Not a few glaciers exhibit this remarkable veined structure throughout their entire extent. When a vertical cutting exposes the delicate azure network to atmospheric influences, the softer ice melts prior to the fusion of the blue ice which then remains in their detached leaflets. On examining these attentively, we cannot fail to remark the absence, or, at all events, the extreme rarity, of air-bubbles, though they are so plentiful in the coarser ice.

Professor Tyndall’s explanation of this phenomenon is as interesting as it is ingenious. While on a visit of inspection to the slate-quarries of Wales, he had occasion to study the _cleavage_ of the rocks which compose them; in other words, their faculty of dividing naturally, a property inherent in all crystals. The schistous slate separates easily into sheets, and in traversing different quarries one sees that all the planes of cleavage are parallel in each. From this circumstance our men of science were at first induced to look upon slates as the products of the stratification of different deposits. Such an explanation, however, could not be accepted by Tyndall, when he observed that the minute fossils embedded in them were constantly misshapen and flattened in the direction of the plane of cleavage, because the great modification they had undergone could not have taken place in superimposed strata at the bottom of the primeval sea. He concluded that these schists, therefore, must have been subjected to a considerable pressure; and further, that this pressure must have been exercised at right angles with the plane of separation of the different layers.

A long series of experiments proved that many bodies, when forcibly compressed, exhibit in their structure a very distinctly marked lamination, and frequently veins of very great beauty.

He carefully examined iron which had passed under the steam-hammer, or through the rolling-mill; clay and wax were subjected to the hydraulic press. In all cases he detected signs of cleavage; and hence we are justified in the inference that the phenomenon is invariably produced by pressure in all bodies of irregular internal structure. Such is the result with glacier-ice, from whose mass the air-bubbles introduced by the snow are gradually expelled. At first of brilliant whiteness, it assumes, in the parallel layers corresponding to the planes of cleavage, those beautiful azure tints which characterize the veined structure. So little has it to do with stratification, that in places where this is apparent it has given rise to a series of horizontal lines, while the parallel veinings, in the same masses of ice, are all inclined at an angle of about 60°.

The tendency to cleavage in compact ice would seem to explain the regular form of those fragments or detached pieces with which some parts of the glaciers are covered. Usually they occur as cubes, or as rectangular parallelopipeds. The Alpine mountaineers name them _séracs_,--in allusion to their resemblance to certain cheeses which bear this name, and which are manufactured in rectangular boxes. They have been found in many parts of a really colossal size, measuring fifty feet in length, breadth, and depth, and as regular in shape as if they had been hewn with a chisel.

There are many interesting points connected with the formation and constitution of glaciers which we should gladly discuss, but we are confined by our limits to remarks of a general character, and we must now pass on to speak of the phenomena attendant upon their motion. No doubt, the traveller who for the first time comes in sight of one of these huge ice-rivers, and sees the mighty mass apparently rooted to its valley-bed, solid, unchangeable, adamantine, finds it hard to believe that it moves onward with a certain and an unresting, though a gradual progress. It looks like a noble river, suddenly petrified by some overwhelming force: congealed, as it flowed, in a moment, by some irresistible spell! Such, indeed, is the conception of the poet:--

“Ye ice-falls! ye that from the mountain’s brow
Adown enormous ravines slope amain....
Torrents, methinks, that heard a mighty voice,
And stopped at once amid their maddest plunge!
Motionless torrents! silent cataracts!”

And this conception is justified by the _aspect_ of the glacier. Thus, of the Glacier du Géant, Professor Tyndall says:--“It stretches smoothly for a long distance, then becomes disturbed, and then changes to a great frozen cascade, down which the ice appears to tumble in wild confusion. Above the cascade you see an expanse of shining snow, occupying an area of some square miles.” But we shall see that here, as in the world of man, appearances are deceitful, and that the glacier well deserves to be called an ice-river, in allusion to its regular and continuous motion.

Between the snow-fall in the higher regions of the globe, and the quantity of snow which every summer disappears through liquefaction, the difference is very considerable. The supply, so to speak, exceeds the demand, and a residuum is annually left. It is only below the perpetual snow-line that the snow created and accumulated in winter is wholly melted in the warm season. And, therefore, if for any considerable period the excess upon any particular mountain continued to accumulate, immense masses of ice would gradually rise to the extreme height in the atmosphere affected by aqueous phenomena.

Rendu, the Roman Catholic prelate, who first led the way to the discovery of the true nature of glaciers, says, very justly,--“The economy of the world would be soon destroyed, if at certain points accumulations of matter prevailed. The centre of gravity of the globe would be insensibly displaced, and the admirable regularity of its movements would be succeeded by disorder and perturbation. If the Poles did not send back to the Equatorial seas the waters which, reduced into vapour, issue daily from these burning regions, to be converted into ice in the Arctic and Antarctic Zones, ocean would be drained dry, and life would cease, as well as water, to circulate throughout our world. The Creator, however, in order to ensure the permanence of His almighty work, has called into existence the vast and powerful law of circulation, and this law the careful observer sees reproduced in all the economy of Nature. The water circulates from the ocean into the air, from the air it spreads over the earth, and from the earth it passes into the seas. The rivers return from whence they came, in order that they may issue forth anew; the air circulates around the globe, and, as it were, upon itself, passing and repassing successively at all the altitudes of the atmospheric column. The elements of every organic substance circulates in changing from the solid to the liquid or aëriform state, and in returning from the latter to the state of solidity or organization. It is not improbable that the universal agent which we designate under the name of fire, light, electricity, and magnetism, has probably also a circle of _circulation_ as extensive as the universe. Should its movements ever be known to us more than they now are, it is probable that they would afford the solution of a host of problems which still defy the intellect of man. Circulation is the law of life, the method of action employed by Providence in the administration of the universe. In the insect, as in the plant, as in the human body, we find a circulation, or rather several circulations,--blood, humours, elements, fire, all which enter into the composition of the individual.”

However fanciful may be some of the amiable prelate’s speculations, it is certain that the glaciers obey this law of circulation. The snow-accumulations in the upper regions are to some extent reduced by the descent of the avalanches,--that is, of masses of snow and ice which detach themselves from the mountain-sides and dash headlong into the valleys below, where they are rapidly melted by the warmer atmosphere. But this would, in itself, be wholly insufficient. Another movement, at once more efficacious and more regular, is necessary; a movement which embraces the entire system of the ice-masses, and which carries the glaciers below the perpetual snow-line, so that every year they may give up a portion of their terminal extremities. The discovery of this general progression is one of the most fertile with which, of late years, the physics of the globe have been enriched.

Professor Tyndall rightly observes that there are numerous obvious indications of the existence of glacier-motion, though it is too slow to catch the eye at once. The crevasses change within certain limits from year to year, and sometimes from month to month; and this could not be if the ice did not move. Rocks and stones also are observed, which have been plainly torn from the mountain-sides. Blocks seen to fall from particular points are afterwards noticed lower down. On the moraines rocks are found of a totally different mineralogical character from those composing the mountains right and left; and in all such cases strata of the same character are found bordering the glacier higher up. Hence the conclusion that the foreign _boulders_ have been _floated_ down by the ice. Further, the ends or “snouts” of many glaciers act like ploughshares on the land in front of them, overturning with irresistible energy the huts and châlets that lie in their path. Facts like these have been long known to the inhabitants of the High Alps, who were thus made acquainted in a vague and general way with the motion of the glaciers. But Science cannot deal with generalities: it requires precise and accurate information; and this information, so far as the progression of the glaciers is concerned, has been obtained through the patient labours of Rendu, Charpentier, Agassiz, Desor, Vogt, Professor Forbes, Bravais, Charles Martins, Hopkins, Professor Tyndall, Colomb, John Ball, and Schlagintweit. Their experiments and observations have established the truth of certain immutable principles, and proved the existence of a general law of movement.

The accumulation of the débris hurled headlong by the mountains forms on the glacier-surface long lines of stone and earth, which are called _moraines_; these diverge in certain directions, according to the circumstances we now come to explain.

The landslips which occur on the banks or edges of the glacier give rise to the _lateral moraines_, which are enlarged and extended daily by the twofold effect of the fall of stones and débris, and the progressive movement which carries them along with the whole mass of ice. Towards the centre of the great glaciers, in almost every case, is found a _medial moraine_; the result of the encounter of the lateral moraines of two glaciers which have united into one. These superficial moraines participating in the movement of the glacier, each of their blocks eventually rolls to the foot of the terminal precipice, and thus a _frontal moraine_ is formed on the very soil of the valley, like an embankment raised to prohibit the further advance of the ice. And, lastly, the bed of sand, gravel, pebbles, and detritus which is found beneath the glacier, and over which it glides, is called the _profound moraine_.

The furrows wrought by this last-named stratum on the bottom of the glacier-channels show the wonderful force of friction which the glacier exercises during its descent. The depths of these furrows depends entirely on the hardness of the débris carried down by the glacier, and the nature of the rocks submitted to the friction. The polish assumed by these rocks when they are sufficiently solid to resist the thunderous march of the glacier, indicates the enormous pressure which it exercises on the slopes of the valley through which it forces its way. This effort, bearing principally on the side of the rocks turned in the direction of their crests, impresses upon them a peculiar rounded form, so like the appearance of a flock of sheep (_moutons_) that De Saussure gave them the name of _roches moutonnées_.

Connected with the scientific evidence of the progressive movement of glaciers, a glacier in the Bernese Oberland will for ever be memorable. Two branch glaciers, the Lauteraar and the Finsteraar, unite at a promontory called the Abschwung to form the trunk-glacier of the Unteraar, which carries a great medial moraine along its colossal back.

Here in 1827, an “intrepid and enthusiastic” Swiss professor, Hugi, of Solothurm (or Soleure), erected a small cabin of stones for the purpose of observations upon the glacier. The hut moved, and he took steps to measure its motion. In three years, 1827 to 1830, it moved 330 feet downwards. In 1836 it had descended 2354 feet; and in 1841, it had accomplished a journey of 4712 feet. [This was at the rate of about 336 feet a year.]

In 1840, M. Agassiz, with some scientific friends, Messrs. Desor, Vogt, and Nicolieb, established themselves under a great overhanging slab of rock on the same moraine, and by means of side walls, and other appliances, constructed a rough abode which, because some of these men of science came from Neufchâtel, they named the “Hôtel des Neuchâtelois.”

In two years after its erection, Agassiz discovered that it had moved downwards no less a distance than 486 feet.

These and some similar measurements brought to light a very important fact. The reader will observe that the _middle numbers_, corresponding to the central portion of the glacier, are the _largest_: hence it was obvious that the _centre of a glacier, like that of a river, moves more rapidly than the sides_.

Owing to the greater central motion of a glacier, its crevasses invariably assume a curved outline, of which the convexity advances towards the bottom of the valley.

It has also been ascertained that the superficial part of a glacier moves more rapidly than its base.

Again: Tyndall and Hirst, by employing instruments of great precision, have demonstrated that the maximum of motion is not to be found exactly in the centre, but that, according to the windings of the valley through which the glacier flows, it moves sometimes to the right of the centre, and sometimes to the left. Now, the progression of a river exhibits all the characters we have just enumerated, and the truth foreshadowed by Rendu has been confirmed in every detail. The glacier _is_ a “river of ice.”

The reader will naturally ask, How can a substance of such apparent rigidity as ice obey, as it _does_ obey, the same laws which regulate the movement of fluids? I can understand, he may say, how water flows in such and such a manner: it is a liquid, and its molecules are deficient in the property of cohesion; but that so solid, and firm, and unimpressible a substance as ice should be capable of motion seems impossible. I can understand very easily that a mass of ice, when loosened or detached from its resting-place, will glide downwards until arrested by some adequate obstacle; but this is not the kind of motion you are describing. According to your explanations, every constituent portion of the glacier moves, and the central faster than the lateral, and the surface faster than the base.

These objections were advanced by men of science when the motion of glaciers was first put forward as a theory; and the answer given by Scheuchzer was, that a glacier might be compared, in the summer season, to a sponge saturated with water, which, when afterwards congealed by the cold temperature of autumn and winter, expanded, and produced a dilatation of the mass in every direction. Then, as it could not recede, as it could not _reascend_ its valley-slope, the augmentation of size would necessarily take place in its lower portion.

It is unnecessary for us to explain why this answer was unsatisfactory. Subsequent observations, however, proved its impossibility, and Professor Forbes then put forward his ideas of the _viscous character_ of ice. But these, too, did not meet the conditions of the phenomenon; and the view now adopted is that of Professor Tyndall, who has shown that it is the result of the regelation we have already described.

Professor Forbes enunciated his theory in words to the following effect: “A glacier is an imperfect fluid or viscous body, which is urged down slopes of certain inclination by the natural pressure of its parts.” But we know the exceeding brittleness of ice, and how is viscosity compatible with brittleness? We know, too, that crevasses and fissures will suddenly form on a glacier, like the cracks on a pane of glass. But if ice were viscous, and could expand, dilate, or stretch as viscous substances do, these crevasses would be impossible. They would gradually close up, like an indent in a mass of jelly. And yet it cannot be denied that a glacier _does_ move like a viscous body; the centre flowing past the sides, the top flowing over the bottom, while the motion through a curved valley corresponds to fluid motion. How are we to reconcile these apparently conflicting circumstances?

By Professor Tyndall’s regelation theory, which is founded on a fact already mentioned; namely, that when two pieces of thawing ice are brought in contact, they freeze together.

This _fact_, and its application irrespective of the _cause_ of regelation, may be thus illustrated: “Saw two slabs from a block of ice, and bring their flat surfaces into contact; they immediately freeze together. Two plates of ice, laid one upon the other, with flannel round them overnight, are sometimes so firmly frozen in the morning that they will rather break elsewhere than along their surface of junction. If you enter one of the dripping ice-caves of Switzerland, you have only to press for a moment a slab of ice against the roof of the cave to cause it to freeze there and stick to the roof.

“Place a number of fragments of ice in a basin of water, and cause them to touch each other; they freeze together where they touch. You can form a chain of such fragments; and then, by taking hold of one end of the chain, you can draw the whole series after it. Chains of icebergs are sometimes formed in this way in the Arctic seas.”

From these observations we deduce the following result:--Snow consists of small particles of ice. Now, if by pressure we squeeze out the air entangled in thawing snow, and bring the little ice-granules into close contact, they may be expected, as they do, to freeze together; and should the expulsion of the air be complete, the squeezed snow will assume the appearance of compact ice.

It is in this way that the consolidation of the snows takes place in the Arctic as in the higher Alpine regions. The deeper layers of the _névé_ are converted into more or less perfect ice by the pressure of the superjacent layers; and further, they are made to assume the shape of the valley which they fill, by the slow and continuous pressure of its sides.

In glaciers, as Professor Tyndall points out, we have ample illustrations of rude fracture and regelation; as, for example, in the opening and closing of crevasses. The glacier is broken on the cascades, and mended at their bases. When two branch glaciers lay their sides together, the regelation is so firm that they begin immediately to flow in the trunk glacier as in a single stream. The medial moraine gives no indication by its slowness of motion that it is derived from the sluggish ice of the sides of the branch glaciers.

We may sum up the regelation theory in few words. The ice of glaciers changes its form and retains its continuity under _pressure_ which keeps its particles together. But when subjected to _tension_, sooner than stretch, it _breaks_, and behaves no longer as a viscous body.

These are Professor Tyndall’s words, and the fact which they embody it would be difficult to set forth more clearly or more concisely.

Having said thus much of the structure, causes, characteristics, and movement of glaciers, we proceed to consider some of the more remarkable of those which are situated in the Arctic World.

The glaciers of the Polar Regions do not differ in structure or mode of formation from those of other countries. Yet they possess some peculiar features, and to a superficial observer might seem independent of the physical laws we have attempted to explain. That this is not the case has been shown by Charles Martins, who carefully studied the glaciers of Spitzbergen on the occasion of the exploring voyage of the _Recherche_ to that island, and has demonstrated that their differences are but a particular case of the general phenomenon.

As special characters he points out, first, the rarity of needles and prisms of ice, which he attributes to the slight inclination and the uniformity of the slopes, as well as to the diminution of the solar heat, which, even in the long summer days, does not melt the surface. There are no rills or streams capable of hollowing out crevasses and moulding protuberances or projections. But transversal crevasses produced by the movement of the glaciers are numerous, and these are often very wide and very deep.

In the terminal escarpment, which melts in proportion as it plunges into the sea, immense caverns are sometimes seen; caverns so immense that the azure-gleaming grottoes of the Arveiron and Grindelwald, so much admired by European travellers, are but miniatures. “One day,” says Charles Martins, “after having ascertained the temperature of the sea off the great glacier of Bell Sound, I proposed to the sailors who accompanied me to carry our boat into its cavern. I explained to them the risk we should incur, being unwilling to attempt anything without their consent. When our boat had crossed the threshold, we found ourselves in an immense Gothic cathedral; long conical-pointed cylinders of ice descended from the roof; the recesses seemed so many chapels opening out of the principal nave; broad fissures divided the walls, and the open intervals, like arches, sprang towards the summits; azure gleams played over the icy surface, and were reflected in the water. The sailors, like myself, were dumb with admiration. But a too prolonged contemplation would have been dangerous; we soon regained the narrow opening through which we had penetrated into this winter temple, and, returning on board our vessel, preserved a discreet silence respecting an escapade which might have been justly blamed. In the evening, we saw from the shore our cathedral of the morning slowly bend forwards, detach itself from the parent glacier, crash into the waves, and reappear in a thousand blocks and fragments of ice, which the retiring tide carried slowly out to sea.”

The Spitzbergen glaciers do not exhibit those numerous moraines which are observed on the majority of those of Switzerland.

The mountains, not being very lofty, are buried, as it were, under their burden of glaciers, instead of preponderating over them, and seem with difficulty to lift their peaks out of the mass of ice and snow surrounding them. Consequently, there are no considerable landslips or falls of earth and stone, which, accumulating along the borders of the glaciers, might form moraines. Martins is of opinion that the Spitzbergen glaciers correspond to the upper part of the glaciers of Switzerland; to so much, that is to say, as lies above the perpetual snow-line.

Now, he says, the higher we ascend on an Alpine glacier, the more do the lateral and medial moraines diminish in width and form, until they taper away and finally disappear under the high _névés_ of the amphitheatres from which the glacier issues, just as the mountain torrents often take their rise in one or in several lakes terraced one above the other.

For all these reasons, he adds, the medial and lateral moraines are scarcely conspicuous on the glaciers of Spitzbergen; a number of stones and boulders may be seen along their sides, and sometimes in their centre, but the ice is never hidden, as in the Alps, under the mass of débris accumulated upon it. As for the terminal moraines, they must be sought at the bottom of the sea, since the terminal escarpment nearly always overhangs it. Hence, the blocks of stone fall simultaneously with the blocks of ice, and form a submarine frontal moraine, of which the two extremities are occasionally visible upon the shore.

In a previous chapter we have alluded to the manner in which icebergs are formed by the detachment from the seaward extremity of the glacier of huge masses of ice, which the current carries out into the open sea. To the description already given, we may here add that which Charles Martins furnishes in his valuable and interesting record of persevering scientific enterprise, “Du Spitzberg au Sahara”:--In Spitzbergen, he says, the glacier, after a traject of more or less considerable duration, reaches the sea. If the shore be rectilineal, it advances no further; but, in the recess of a bay, where the shore is curved, it continues its progression, supporting its bulk on the sides of the bay, and advancing above the water, which it overhangs. This is easily understood. In summer the sea-water at the bottom of the bays is always at a temperature a little above 32°; on coming in contact with this comparatively warm water the glacier melts, and, at low tide, an interval is perceptible between the ice and the surface of the water. The glacier being no longer supported, partially crumbles and gives way; immense blocks detach themselves, fall into the sea, disappear beneath the water, reappear revolving on their own axes, and oscillate for a few moments until they have taken up their position of equilibrium. The blocks thus detached from the floating masses, of all sizes and shapes, are called icebergs.

Our traveller records that twice a day, in Magdalena Bay and Bell Sound, he was an eye-witness of this partial ruin of the extremity of the glaciers. Their fall was accompanied by a noise like that of thunder; the swollen sea rushed upon the shore in a succession of gigantic waves; the gulf was covered with icebergs, which, caught in the swirl and eddy, issued out of the bay, like immense fleets, to gain the sea beyond, or were stranded here and there at points where the water was shallow. The icebergs seen by M. Martins were not, however, of any surprising magnitude; he estimates their average height at thirteen to sixteen feet. We have seen that those of Baffin Bay are tenfold more considerable and imposing; but then, in that bay the temperature of the sea is below 32°; the glacier does not melt when it enters the water; it sinks to the bottom of the sea; and the portions detached from it are all of greater height than even the submerged part of the icebergs which drift to and fro in the bays and gulfs of Spitzbergen.

* * * * *

We may follow up this description with some observations by Lieutenant Bellot, the chivalrous young Frenchman who perished in one of the expeditions despatched in search of Sir John Franklin and his companions. He is speaking of the masses of ice his ship encountered soon after doubling Cape Farewell, the south point of Greenland, and he remarks, that as Baffin Bay narrows towards the south, the icebergs, first set in motion higher up the bay by the northern gales, necessarily tend to accumulate in the gorge thus formed, and so to impede and block up Davis Strait, even when the higher waters are quite free. It is only through a series of alternate movements of advance and recession that the bergs finally pass beyond the barrier, and float out into the Atlantic, to undergo a slow process of dissolution.

The mobility of the bergs, though necessary to navigation, forms at the same time its peculiar danger, since a vessel is often placed between the shore and the colossal masses driven forward by the wind, or between these and the solid ice which as yet has not broken up. It is useless to dwell upon the immense force possessed by masses which are frequently several square leagues in extent, and which, once in movement, cannot be stayed by any human resistance. A sailing-vessel finds herself placed in conditions all the more unfavourable, because the winds blow from the very direction which she is bound to take in order to open up a way through the floes. Now, if the gale is violent, it is perilous indeed to push forward in the midst of a labyrinth of bergs, which form so many floating rocks; if a calm prevails, a ship can move forward only by laborious hauling or towed by the boats. The application of the screw-propeller to steam-ships has given to them a great superiority, because they are not liable to any accident to paddle-wheels, exposed as such must be to collision with the floating ice. It is recorded that, on one occasion, a screw-steamer, near Upernavik, on the coast of Greenland, actually _charged_ an iceberg, and drove right through it, as a railway-engine might crash through a fence or hurdle. Of course, the berg was of no great elevation; but its solid mass yielded to the immense force of the steamship, and split into large fragments.

In the convulsions caused by furious tempests, which are far from being so rare within the Arctic Circle as is popularly supposed, the shape of the bergs becomes very irregular, and the configuration of the ice-fields is constantly undergoing modification. Hence it often happens that the voyager sees before him an open basin of water of greater or less extent, from which he is separated only by a narrow strip of ice. In such a case he endeavours to effect an opening, either by driving his ship at full speed against the weakest part of the ice, or with the help of immense saws, twenty feet in length, which are worked with a rope and pulley placed at the top of a triangle formed of long poles; or, finally, by exploding a mine. When the ice is not very solid, the ship is forced into the opening, against the sides of which it acts like a wedge. It will sometimes occur, in the course of the operation, that the ice-fields, set in motion by the wind or the currents, close in together, after having treacherously separated for a moment, and the vessel is then subjected to a dangerous pressure. Unhappy the mariner who does not foresee or sufficiently note the warning signs of this accident, which is almost always accompanied by fatal consequences. The ice, which nothing can check, passing underneath the ship, capsizes it,--or, if it resists, crushes it.

* * * * *

We have alluded to the colossal bergs of Baffin Bay. These are thrown off from the northern glaciers, and particularly from the enormous ice-river named after Humboldt, which cumbers the declivities of the Greenland Alps, beyond the 79th parallel. It has been a frequent source of surprise to navigators that these mighty masses should float in a contrary direction to that of the ice-fields which descend with the Polar current towards the Atlantic. They reascend with such rapidity that they shatter the so-called “ice-foot,” or belt of ice, still adhering to the shore. Captain Maury has collected numerous observations on this important subject, and he quotes the case of a ship which was being laboriously hauled against the current, when an enormous floating mountain coming up from the south steered against it, but fortunately did not come into collision with it, and forging ahead, very quickly disappeared. How is such an incident to be explained? By the existence of a submarine counter-current, acting on the lower extremity of the submerged portion of the berg, which, as we have stated, is always seven or eight times larger than the bulk _above_ the surface of the waves.

Our whalers, in their hazardous expeditions, often derive assistance from these moving islands. They seek shelter under their lee when sudden storms arise; for the huge bergs are scarcely affected by the most violent gales. They find their shelter valuable also during certain operations of the fishery for which rest and quiet are necessary. Yet it is not absolutely exempt from danger. The seeming friend may prove to be a concealed foe. The iceberg may collapse, or be capsized; or formidable fragments, loosened from their sides or summits, may topple headlong and threaten to overwhelm the ship beneath: but as on these and other accidents we have already dwelt at length, we refrain from wearying our readers with a twice-told tale. The repetition in which, to some extent, we have indulged, was needful, in order to show the reader in what way the dissolution of the lower extremity of the glaciers is effected in the Arctic world.

* * * * *

In the neighbourhood of Cape Alexander, one of the headlands of Smith Strait, Dr. Hayes met with a glacier, of which he gives an interesting description in his narrative of an “Arctic Boat Journey,” (1854):--

It was the first, protruding into the ocean, which he had had an opportunity of inspecting closely; and though small, compared with other similar formations, it had nevertheless all their principal characteristics. It presented to the sea a convex mural face, seventy feet in height and about two miles in length, its centre projecting into the water beyond the general line of the coast to the east and west of it. The surface rose abruptly to the height of about two hundred feet, and, sloping thence backward with a gentle inclination, seemed to be connected with an extensive _mer de glace_ above. Several fissures or crevasses, apparently of great depth, struck vertically through its body, and extended far up into its interior; and others, more shallow, which seemed to have been formed by the streams of melted snow that poured in cataracts down into the sea. Dr. Hayes remarks that he was impressed by its viscous appearance; but we have shown that a certain amount of viscosity naturally appertains to glacier ice.

Parallel with its convex face ran a succession of indistinctly marked lines, which gave it the aspect of a semi-fluid mass moving downward upon an inclined surface; and this idea was confirmed by its appearance about the rocks on either side. Over these it seemed to have flowed; and, fitting accurately into all their inequalities, it gave the effect of a huge moving mass of partially solidified matter suddenly congealed.

* * * * *

Of still greater interest is the same adventurous explorer’s description of the great Arctic _Mer de Glace_ which lies inland from Rensselaer Bay, in about lat. 79° N., and long. 68° W.

Dr. Hayes and his party had set out on an expedition into the interior, and after passing through a really picturesque landscape, enriched with beds of moss and turf, patches of purple andromeda, and the trailing branches of the dwarf-willow, they emerged upon a broad plain or valley, in the heart of which reposed a frozen lake, about two miles in length by half a mile in width. They traversed its transparent surface. On either side of them rose rugged bluffs, that stretched off into long lines of hills, culminating in series in a broad-topped mountain-ridge, which, running away to right and left, was cut by a gap several miles wide that opened directly before them. Immediately in front was a low hill, around the base of which flowed on either side the branches of a stream whose course they had followed. Leaving the river-bed just above the lake, they climbed to the summit of this hillock; and there a sight burst upon them, grand and imposing beyond the power of words adequately to describe. From the rocky bed, only a few miles in advance, a sloping wall of pure whiteness rose to a broad level plain of ice, which, apparently without limits, stretched away toward the unknown east. It was the great _mer de glace_ of the Arctic continent.

Here then was, in reality, the counterpart of the river-systems of other lands. From behind the granite hills the congealed drainings of the interior water-sheds, the atmospheric precipitations of ages, were moving in a mass, which, though solid, was plastic, moving down through every gap in the mountains, swallowing up the rocks, filling the valleys, submerging the hills: an onward, irresistible, crystal tide, swelling to the ocean. The surface was intersected by numerous vertical crevasses, some of considerable depth, which had drained off the melted snow.

It was midnight when the explorers approached this colossal reservoir. The sun was several degrees beneath the horizon, and afforded a faint twilight-gleam. Stars of the second magnitude were dimly perceptible in the cold, steel-blue Arctic heavens. When they were within about half a mile of the icy wall, a brilliant meteor fell before them, and, by its reflection upon the glassy surface beneath, greatly increased the magical effect of the scene; while loud reports, like distant thunder or the roll of artillery, broke at intervals from the depths of the frozen sea.

On closer inspection it was found that the face of the glacier ascended at an angle of from 30° to 35°. At its base lay a high bank of snow, and the wanderers clambered up it about sixty feet; but beyond this their efforts were defied by the exceeding smoothness of the ice. The mountains, which stood on either hand like giant-warders, were overlapped, and to some extent submerged, by the glacier. From the face of the huge ice-river innumerable little rivulets ran down the channels their action had gradually excavated, or gurgled from beneath the ice; forming, on the level lands below, a sort of marsh, not twenty yards from the icy wall. Here, in strange contrast, bloomed beds of verdurous moss; and in these, tufts of dwarf-willows were wreathing their tiny arms and rootlets about the feebler flower-growths; and there, clustered together, crouching among the grass, and sheltered by the leaves, and feeding on the bed of lichens, flourished a tiny, white-blossomed draba and a white chickweed. Dotting the few feet of green around might be seen the yellow flowers of the more hardy poppy, the purple potentilla, and saxifrages yellow, purple, and white.

* * * * *

The great glacier of Sermiatsialik is one of the arms, or outlets, of this immense reservoir of ice. It occupies the bed of a valley, varying from three and a half to five miles in width, and attaining at certain points a depth of upwards of three hundred and seventy feet. This valley opens upon the fiord of Sermiatsialik, which is separated from that of Julianshaab by the range of mountains culminating in the peak of Redkammen.

We owe to Dr. Hayes a lively description of the Sermiatsialik glacier, which he thinks must at some places be more than seven hundred and fifty feet in depth, overflowing the borders of the valley like a swollen torrent. For upwards of four leagues, the icebergs which throng the fiord, or gulf, are those of the glacier itself, and terminating in a wedge-like outline, disappear in the vast sea of ice expanding to right and left above the loftiest summits, and drawing irresistibly the eye to its rippled surface,--boundless, apparently, like that of ocean. As the voyager sails up the gulf, he gradually loses sight of the frozen slope, and then of the white line of the _mer de glace_: he finds himself in front of an immense cliff, from one hundred to two hundred feet in height, diaphanous as the purest crystals, and reflecting all the hues of heaven.

One almost shudders as one approaches this vast domain of Winter. Collecting in copious streams, the ice and snow melted on the surface of the glacier pour over its brink, forming floating clouds of spray, irradiated by rainbow colours. The din of these cascades fills the air. At intervals, the loud reports of the internal convulsions of the glacier are repeated by every echo.

The cliff is entirely vertical; but its face, far from being smooth, is broken up into an infinite variety of forms: into unfathomable cavernous hollows, symmetrical spires, ogives, pinnacles, and deep fissures, where the eye plunges into a transparent blue, which changes every second its fleeting, opaline tints; tints so soft, and yet so vivid, that they defy the skill of the artist to reproduce them. The lustre of the “dark eye of woman” is not more difficult to seize. A deep dark green, less delicate but not less splendid, colours all the recesses where the ice overhangs the waters. In the sunlight one sees the surface of these huge crystals shining with the whiteness of the purest snow; except, indeed, where recent fractures have taken place. They suggest to the mind the idea of the gleams and reflections of a piece of satin; the undulatory lustre and shifting sparkle being produced by the different angles under which the light is reflected.

* * * * *

But let us suppose that we have landed; with much difficulty have ascended the cliffs; and have clambered up the glacier to its very summit. The scene before us, how shall we convey to the mind of the reader?

Imagine, if you can, the rapids of the Upper Niagara congealed even to their lowest depths; imagine the falls, and the broad river, and the great Lake Erie all frozen into solid ice; with bergs above the cataract towering as high as the lower banks: suppose that you, the spectator, having taken your stand upon the rapids, with the Erie so near that you can see its crystallized surface, and you will have a picture, on a reduced scale, of the sea of ice now spreading far before us. The rapids will represent the glacier; the Great Fall the cliff which it projects into the sea (only that the celebrated “horse-shoe” is here turned outwards); the river which broadens into the Ontario will be the fiord; and the Ontario, that dark grim ocean into which the gigantic bergs detached from the mighty ice-cascade are slowly making their way!

* * * * *

We must indicate, however, one remarkable dissimilarity, for which our previous observations on the nature of glaciers will have prepared the reader. From one bank to the other, the surface of a river is always _horizontal_, but that of a glacier is slightly _convex_.

Through the narrow glen, or ravine, formed by this curvature of the glacier, a kind of lateral trough or gully, bounded by the escarpment of the soil, we reach the sea. The descent is not without its dangers, for at every point crevasses open, separated by slippery projections. These deep gashes, at some points, are only a few yards apart; and they incessantly cross each other, and run into one another, so as to form a perfect labyrinth, in the windings of which the adventurous traveller is apt to feel bewildered.

The border of the glacier once crossed, the way becomes less difficult; for a mile and a half the level is almost perfect, and the ice but little broken up. The frozen desert, however, impresses us with an almost solemn feeling, and there is something terrible in the desolation of such a Sahara of snow!

Moreover, the traveller is irresistibly affected by the continual roar or growling of the enormous mass, which seems to stir and shake under our very feet. He would not be surprised if a vast chasm suddenly yawned before him! These harsh deep voices of the glacier, however, are not the only sounds we hear. On every side rises the murmur of brooks which trace their furrows across the crystalline plain. Some of these gradually converge, and, uniting, form a considerable torrent, which leaps with a clang from icy crag to icy ledge, until it is lost in a crevasse, or precipitated over the frozen cliff into the waters of the fiord. The _solitude_ of the scene is complete, but not the _silence_. The air is as full of “noises” as ever was Prospero’s isle.

Such are the principal features of the glacier of Sermiatsialik.

* * * * *

About ninety miles north-east of Rensselaer Bay lies the great Humboldt Glacier, which seems to serve as a connecting-link between the Old World and the New.

It lies between the 79th and 80th parallels north, and between the 64th and 65th meridians west, skirting the shore of Peabody Bay, which is a bold indentation of the east coast of Kane Sea.

It was discovered in Dr. Kane’s expedition, and is probably one of the grandest spectacles in the Arctic world. Dr. Kane acknowledges himself unable to do justice to its magnificent aspect. He can speak only of its “long, ever-shining line of cliff diminished to a well-pointed wedge in the perspective;” of its “face of glistening ice, sweeping in a long curve from the low interior, the facets in front intensely illuminated by the sun.”

This line of cliff rises, like a solid wall of glass, three hundred feet above the water-level, with an unknown, unfathomable depth below it; and its curved face, _sixty miles in length_, disappears into unknown space at not more than a single day’s railroad-travel from the Pole. The interior with which it communicates, and from which it issues, is an unexplored _mer de glace_, an ice-ocean, of apparently boundless dimensions.

Such is the “mighty crystal bridge” which connects the two continents of America and Greenland. We say, continents; for Greenland, as Dr. Kane remarks, however insulated it may ultimately prove to be, is in mass strictly continental. Its least possible axis, measured from Cape Farewell to the line of the Humboldt Glacier, in the neighbourhood of the 80th parallel, gives a length of upwards of twelve hundred miles,--not materially less than that of Australia from its northern to its southern cape.

Imagine the centre of such a continent, says Dr. Kane, occupied through nearly its whole extent by a deep, unbroken sea of ice, that gathers perennial increase from the watershed of vast snow-covered mountains and all the precipitations of the atmosphere upon its own surface. Imagine this, moving onward like a great glacial river, seeking outlets at every fiord and valley, rolling icy cataracts into the Atlantic and Greenland seas; and, having at last reached the northern limit of the land that has borne it up, pouring out a mighty frozen torrent into unknown Arctic space.

“It is thus,” remarks Dr. Kane, “and only thus, that we must form a just conception of a phenomenon like this great glacier. I had looked in my own mind for such an appearance, should I ever be fortunate enough to reach the northern coast of Greenland. But now that it was before me, I could hardly realize it. I had recognized, in my quiet library at home, the beautiful analogies which Forbes and Studer have developed between the glacier and the river; but I could not comprehend at first this complete substitution of ice for water.

“It was slowly the conviction dawned on me that I was looking upon the counterpart of the great river-system of Arctic Asia and America. Yet here were no water-feeders from the south. Every particle of moisture had its origin within the Polar Circle, and had been converted into ice. There were no vast alluvions, no forest or animal traces borne down by liquid torrents. Here was a plastic, moving, semi-solid mass, obliterating life, swallowing rocks and islands, and ploughing its way with irresistible march through the crust of an investing sea.”

* * * * *

When, at a later period, Dr. Kane made a closer examination of this great natural wonder, he found that previously he had not realized the full grandeur of the spectacle. He noted that the trend of the glacier was a few degrees to the west of north; and he remarks, as the peculiarity of its aspect, that it did not indicate _repose_, but activity, energy, movement.

Its surface seemed to follow that of the basis-country over which it flowed. It was undulating on and about the horizon, but as it descended towards the sea it represented a broken plain with a general inclination of some nine degrees, still diminishing toward the foreground. Crevasses, which in the distance seemed like mere wrinkles, expanded as they came nearer, and were intersected almost at right angles by long continuous lines of fracture parallel with the face of the glacier.

These lines, too, scarcely perceptible in the far distance, widened as they approached the sea until they formed a gigantic stairway. It seemed as though the ice had lost its support below, and that the mass was let down from above in a series of steps; and such an action is the necessary result of the heat thrown out by the soil, the excessive surface-drainage, and the constant abrasion of the sea.

The indication of a great propelling agency seemed to be just commencing at the time that Dr. Kane visited the great glacier. The split-off lines of ice were evidently in motion, pressed on by those behind, but still broadening their fissures, as if the impelling action grew more and more energetic nearer the water, till at last they floated away in the form of icebergs. Long files of these detached masses might be seen, like the ranks of a stately armada, slowly sailing out into the remote sea, their separation marked by dark parallel shadows; broad and spacious avenues near the eye, but narrowed in the perspective to mere furrows. A more impressive illustration of the forces of nature it would be difficult to conceive.

Dr. Kane’s view of the formation of icebergs differs considerably from that which most physicists entertain.

He does not believe that the berg falls into the sea, broken by its weight from the parent glacier; he is of opinion that it _rises from_ the sea. The process is at once gradual and comparatively quiet. “The idea of icebergs being discharged, so universal among systematic writers, seems to me at variance with the regulated and progressive actions of Nature. Developed by such a process, the thousands of bergs which throng the Polar seas should keep the air and water in perpetual commotion, one fearful succession of explosive detonations and propagated waves. But it is only the lesser masses falling into deep waters which could justify the popular opinion. The enormous masses of the great glacier are propelled, step by step and year by year, until, reaching water capable of supporting them, they are floated off to be lost in the temperatures of other regions.”

The Humboldt Glacier did not differ in structure from the Alpine and Norwegian ice-growths; and its face presented nearly all the characteristic features of the latter. The _overflow_, or viscous overlapping of the surface, was very strongly marked. “When close to the island rocks,” says Kane, “and looking out upon the upper table of the glacier, I was struck with the homely analogy of the batter-cake spreading itself out under the ladle of the housewife, the upper surface less affected by friction, and rolling forward in consequence.”

* * * * *

The crevasses bore the marks of direct fracture, as well as of the more gradual action of surface-drainage. The extensive watershed between their converging planes gave to the icy surface most of the hydrographic features of a river-system. The ice-born rivers which divided them were margined occasionally with spires of discoloured ice, and generally lost themselves in the central areas of the glacier before reaching its foreground. Occasionally, too, the face of the glacier was cut by vertical lines, which, as in the Alpine examples, were evidently outlets for the surface drainage.

The height of this ice-wall at the nearest point was about three hundred feet, measured from the water’s edge; and the unbroken right line of its diminishing perspective showed that this might be regarded as its constant measurement. It seemed, in fact, a great icy table-land, abutting with a clean precipice against the sea. This, indeed, is the great characteristic of all those Arctic glaciers which issue from central reservoirs or _mers de glace_ upon the fiords or bays, and is strikingly in contrast with the dependent or hanging glacier of the ravines, where every line and furrow and chasm seem to indicate the movement of descent and the mechanical disturbances which have impeded and delayed it.

Dr. Kane named this monster glacier after Alexander Von Humboldt, to whose labours Physical Science is so largely indebted; and the cape which flanks it on the Greenland coast after the distinguished naturalist, whom the world has so recently lost, Professor Agassiz.

The point at which the Humboldt Glacier enters the “Land of Washington” affords even at a distance very clear indications of its plastic or semi-solid character. The observer finds it impossible to resist the impression of fluidity conveyed by its peculiar markings. Dr. Kane very appropriately named it Cape Forbes, in honour of the illustrious son of Scotia who contributed so largely to our true knowledge of the structure and mode of progression of glaciers.

As the surface of the glacier, adds its discoverer, receded to the south, its face seemed broken with piles of earth and rock-stained rubbish, until far back in the interior it was concealed from view by the slope of a hill. But even beyond this point its continued extension was shown by the white glare or ice-blink in the sky above.

Its outline to the northward could not be so easily traced, on account of the enormous discharges at its base. The talus of its descent from the interior, looking far off to the east, ranged from 7° to 15°; so interrupted by the crevasses, however, as only in the distance to produce the effect of an inclined plane. A few black protuberances rose above the glittering surface of the snow, like islands in a foamy sea.

It could be seen, from the general inequalities of its surface, how well the huge mass adapted itself to the inequalities of the basis-country beneath. The same modifications of hill and dale were discernible as upon land. Thus grand and various in its imposing aspect, it stretches to the north until it touches the new Land of Washington, cementing together by an apparently indissoluble tie the Greenland of the Norse Vikings and the America of the Anglo-Saxon colonists.